How to calculate intensity of a particular color in an RGB image

I have an rgb image with varied intensity of the colour green. How can i determine the intensity?

Answer 1

[Image Analyst]

To get a matrix with the gray level intensities of the three different color channels, use imsplit:

[r, g, b] = imsplit(rgbImage);

g will be a matrix of your green intensities. If you want the overall intensity considering the other color channels, you can use

hsvImage = rgb2hsv(rgbImage);
[h, s, v] = imsplit(hsvImage);

and look at the v channel, or

labImage = rgb2lab(rgbImage);
[L, a, b] = imsplit(labImage);

and look at the L image, or

ycbcrImage = rgb2ycbcr(rgbImage);
[Y, Cb, Cr] = imsplit(ycbcrImage);

and look at the Y image.

[Suyog Pathare]

Thanks! It works